Remove unnecessary cfgs, include Android, switch to socket fd as para…

…meter

src/backend/libc/net/mod.rs

@@ -8,7 +8,7 @@ pub(crate) mod ext;
     target_os = "wasi"
 )))]
 pub(crate) mod msghdr;
-#[cfg(target_os = "linux")]
+#[cfg(linux_kernel)]
 pub(crate) mod netdevice;
 pub(crate) mod read_sockaddr;
 pub(crate) mod send_recv;

src/backend/libc/net/netdevice.rs

@@ -5,13 +5,11 @@ use crate::alloc::string::String;
 use crate::backend::io::syscalls::ioctl;
 use crate::fd::AsFd;
 use crate::io;
-use crate::net::netdevice::open_socket;
 #[cfg(feature = "alloc")]
 use libc::SIOCGIFNAME;
 use libc::{__c_anonymous_ifr_ifru, c_char, ifreq, IFNAMSIZ, SIOCGIFINDEX};
 
-#[cfg(target_os = "linux")]
-pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
+pub(crate) fn name_to_index(fd: impl AsFd, if_name: &str) -> io::Result<u32> {
     let if_name_bytes = if_name.as_bytes();
     if if_name_bytes.len() >= IFNAMSIZ as usize {
         return Err(io::Errno::NODEV);
@@ -25,22 +23,20 @@ pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
     let mut if_name_c_char_iter = if_name_bytes.iter().map(|byte| *byte as c_char);
     ifreq.ifr_name[..if_name_bytes.len()].fill_with(|| if_name_c_char_iter.next().unwrap());
 
-    let fd = open_socket()?;
     unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX as _, &mut ifreq as *mut ifreq as _) }?;
     let index = unsafe { ifreq.ifr_ifru.ifru_ifindex };
     Ok(index as u32)
 }
 
-#[cfg(all(target_os = "linux", feature = "alloc"))]
-pub(crate) fn index_to_name(index: u32) -> io::Result<String> {
+#[cfg(feature = "alloc")]
+pub(crate) fn index_to_name(fd: impl AsFd, index: u32) -> io::Result<String> {
     let mut ifreq = ifreq {
         ifr_name: [0; 16],
         ifr_ifru: __c_anonymous_ifr_ifru {
             ifru_ifindex: index as _,
         },
     };
 
-    let fd = open_socket()?;
     unsafe { ioctl(fd.as_fd(), SIOCGIFNAME as _, &mut ifreq as *mut ifreq as _) }?;
 
     if let Some(nul_byte) = ifreq.ifr_name.iter().position(|char| *char == 0) {

src/backend/linux_raw/net/mod.rs

@@ -1,6 +1,6 @@
 pub(crate) mod addr;
 pub(crate) mod msghdr;
-#[cfg(target_os = "linux")]
+#[cfg(linux_kernel)]
 pub(crate) mod netdevice;
 pub(crate) mod read_sockaddr;
 pub(crate) mod send_recv;

src/backend/linux_raw/net/netdevice.rs

@@ -5,14 +5,12 @@ use crate::alloc::string::String;
 use crate::backend::io::syscalls::ioctl;
 use crate::fd::AsFd;
 use crate::io;
-use crate::net::netdevice::open_socket;
 use linux_raw_sys::ioctl::SIOCGIFINDEX;
 #[cfg(feature = "alloc")]
 use linux_raw_sys::ioctl::SIOCGIFNAME;
 use linux_raw_sys::net::{ifreq, ifreq__bindgen_ty_1, ifreq__bindgen_ty_2, IFNAMSIZ};
 
-#[cfg(target_os = "linux")]
-pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
+pub(crate) fn name_to_index(fd: impl AsFd, if_name: &str) -> io::Result<u32> {
     let if_name_bytes = if_name.as_bytes();
     if if_name_bytes.len() >= IFNAMSIZ as usize {
         return Err(io::Errno::NODEV);
@@ -24,22 +22,20 @@ pub(crate) fn name_to_index(if_name: &str) -> io::Result<u32> {
     };
     unsafe { ifreq.ifr_ifrn.ifrn_name[..if_name_bytes.len()].copy_from_slice(if_name_bytes) };
 
-    let fd = open_socket()?;
     unsafe { ioctl(fd.as_fd(), SIOCGIFINDEX, &mut ifreq as *mut ifreq as _) }?;
     let index = unsafe { ifreq.ifr_ifru.ifru_ivalue };
     Ok(index as u32)
 }
 
-#[cfg(all(target_os = "linux", feature = "alloc"))]
-pub(crate) fn index_to_name(index: u32) -> io::Result<String> {
+#[cfg(feature = "alloc")]
+pub(crate) fn index_to_name(fd: impl AsFd, index: u32) -> io::Result<String> {
     let mut ifreq = ifreq {
         ifr_ifrn: ifreq__bindgen_ty_1 { ifrn_name: [0; 16] },
         ifr_ifru: ifreq__bindgen_ty_2 {
             ifru_ivalue: index as _,
         },
     };
 
-    let fd = open_socket()?;
     unsafe { ioctl(fd.as_fd(), SIOCGIFNAME, &mut ifreq as *mut ifreq as _) }?;
 
     if let Some(nul_byte) = unsafe { ifreq.ifr_ifrn.ifrn_name }

src/net/mod.rs

@@ -16,7 +16,7 @@ mod types;
 #[cfg(windows)]
 mod wsa;
 
-#[cfg(target_os = "linux")]
+#[cfg(linux_kernel)]
 pub mod netdevice;
 pub mod sockopt;
 

src/net/netdevice.rs

@@ -1,84 +1,99 @@
 //! Low-level Linux network device access
 //!
+//! The methods in this module take a socket's file descriptor to communicate with
+//! the kernel in their ioctl call:
+//! - glibc uses an `AF_UNIX`, `AF_INET`, or `AF_INET6` socket.
+//! The address family itself does not matter and glibc tries the next address family if socket creation with one fails.
+//! - Android (bionic) uses an `AF_INET` socket.
+//! - Both create the socket with `SOCK_DGRAM|SOCK_CLOEXEC` type/flag.
+//! - The [man-pages] specify, that the ioctl calls "can be used on any socket's file descriptor regardless of the
+//! family or type".
+//!
 //! # References
 //! - [Linux]
 //!
+//! [man-pages]: https://man7.org/linux/man-pages/man7/netdevice.7.html
 //! [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
 
 #[cfg(feature = "alloc")]
 use crate::alloc::string::String;
-use crate::fd::OwnedFd;
+use crate::fd::AsFd;
 use crate::io;
-use crate::io::Errno;
-use crate::net::{socket, AddressFamily, SocketType};
-
-/// Creates a socket used to communicate with the kernel in the ioctl calls.
-#[cfg(target_os = "linux")]
-pub(crate) fn open_socket() -> io::Result<OwnedFd> {
-    if let Ok(fd) = socket(AddressFamily::UNIX, SocketType::DGRAM, None) {
-        Ok(fd)
-    } else if let Ok(fd) = socket(AddressFamily::INET, SocketType::DGRAM, None) {
-        Ok(fd)
-    } else if let Ok(fd) = socket(AddressFamily::INET6, SocketType::DGRAM, None) {
-        Ok(fd)
-    } else {
-        Err(Errno::NOENT)
-    }
-}
 
 /// `ioctl(fd, SIOCGIFINDEX, ifreq)`—Returns the interface index for a given name.
 ///
+/// See the [module-level documentation] for information about `fd` usage.
+///
 /// # References
 ///  - [Linux]
 ///
+/// [module-level documentation]: self
 /// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
 #[inline]
 #[doc(alias = "SIOCGIFINDEX")]
-#[cfg(target_os = "linux")]
-pub fn name_to_index(if_name: &str) -> io::Result<u32> {
-    crate::backend::net::netdevice::name_to_index(if_name)
+pub fn name_to_index(fd: impl AsFd, if_name: &str) -> io::Result<u32> {
+    crate::backend::net::netdevice::name_to_index(fd, if_name)
 }
 
 /// `ioctl(fd, SIOCGIFNAME, ifreq)`—Returns the interface name for a given index.
 ///
+/// See the [module-level documentation] for information about `fd` usage.
+///
 /// # References
 ///  - [Linux]
 ///
+/// [module-level documentation]: self
 /// [Linux]: https://man7.org/linux/man-pages/man7/netdevice.7.html
 #[inline]
 #[doc(alias = "SIOCGIFNAME")]
-#[cfg(all(target_os = "linux", feature = "alloc"))]
-pub fn index_to_name(index: u32) -> io::Result<String> {
-    crate::backend::net::netdevice::index_to_name(index)
+#[cfg(feature = "alloc")]
+pub fn index_to_name(fd: impl AsFd, index: u32) -> io::Result<String> {
+    crate::backend::net::netdevice::index_to_name(fd, index)
 }
 
 #[cfg(test)]
 mod tests {
     use crate::backend::net::netdevice::{index_to_name, name_to_index};
+    use crate::net::{AddressFamily, SocketFlags, SocketType};
 
     #[test]
-    #[cfg(target_os = "linux")]
     fn test_name_to_index() {
+        let fd = crate::net::socket_with(
+            AddressFamily::INET,
+            SocketType::DGRAM,
+            SocketFlags::CLOEXEC,
+            None,
+        )
+        .unwrap();
+
         let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
             .unwrap()
             .as_str()
             .split_at(1)
             .0
             .parse::<u32>()
             .unwrap();
-        assert_eq!(Ok(loopback_index), name_to_index("lo"));
+        assert_eq!(Ok(loopback_index), name_to_index(fd, "lo"));
     }
 
     #[test]
-    #[cfg(all(target_os = "linux", feature = "alloc"))]
+    #[cfg(feature = "alloc")]
     fn test_index_to_name() {
+        let fd = crate::net::socket_with(
+            AddressFamily::INET,
+            SocketType::DGRAM,
+            SocketFlags::CLOEXEC,
+            None,
+        )
+        .unwrap();
+
         let loopback_index = std::fs::read_to_string("/sys/class/net/lo/ifindex")
             .unwrap()
             .as_str()
             .split_at(1)
             .0
             .parse::<u32>()
             .unwrap();
-        assert_eq!(Ok("lo".to_owned()), index_to_name(loopback_index));
+        assert_eq!(Ok("lo".to_owned()), index_to_name(fd, loopback_index));
     }
 }